I think there's lots of reasons. I may or may not have work/worked for a bank. Typically, they use HSA's tied to large range systems like z/OS that generate the seed. The seeds themselves are secure and are not really prone to time attacks like authenticator apps/soft tokens sometimes are.

Its a stupid trade off tbh. However, I think its less likely for people to call in frantic because they can't get into their bank account because everyone are more likely to retain access to their phone and/or email than for the bank to support a 3rd party authenticator app that may or may not be backed up from another 3rd party software.

Also, over time, the authenticator apps can get off sync by a few seconds. That's why its typically offset by 30 seconds when you set it up on most sites, which lessens the likelihood of it getting too off sync for it to work. However, it widens the gaps for time based attacks to bypass 2fa altogether. RSA Securid, I believe, is only like 3 seconds by default but don't quote me on that. That's why you gotta replace the hard tokens for those every 60 months. The battery in them slows down the clock and it gets out of sync.

I could be wrong, but i believe every time you shut your phone off, technically, gets your soft tokens out of sync ever so slightly too. I once had an authenticator app on a phone where the battery died or something that prevented me from turning it back on. It took like a month or two before I could get back in it. By the time I did, none of the soft tokens worked anymore because it became offset by more than 30 seconds.

I've filed about 7 complaints to the Ombudsman where I live for my bank. I refuse to use sms for verification. I blame the bank for limiting my access to my accounts as a result. I've spoken to hundreds of employees, for hours and hours, wasted in branch time for hours, spoken with managers, escalated numerous tickets.

I've probably wasted more of their time and money, then it would have been for them to just implement 2fa from an app rather than sms..

I've proven to them how insecure it is. Employees and managers tell me I'm paranoid for nothing.

I'm so sick of this fight with them. Literally have no idea what else to do other then constantly complain, open tickets hourly and literally waste their time, ruin their metrics and annoy the hell out of anyone that works at the bank. I won't use sms for 2fa.

I bet its the cheapest and/or easiest to implement. Why do more than the bare minimum, amirite?

^I feel like mine is a bad faith opinion, but I also feel passionately about this and want to ensure your post is getting some level of engagement so it can maybe get some proper discussion going.

@Jerry@hear-me.social Honestly, it's a "reach" reason. most people have a phone capable of receiving texts or a voice message (An actual call). Not everyone has a smartphone (or the technical chops to get a legitimate OTP app and setup TOTP). Is that an excuse to NOT offer TOTP or other better MFA options? No it isn't, but then they probably decided to not pay the extra 10c per user for the additional auth option. Cost/benefit analysis, with security not even being a part. If you want your banks to support more robust auth, hound the financial regulators to start making it a requirement.

Oh come on, the US is usually two decades behind modern banking, 2FA over SMS is only a decade behind, so it's an improvement!

You'll have 2FA via an app like the rest of us, but in 2034

Now run along and enjoy your chip and pin

My CU offers auth app support. Yet my big name options provider doesn't. It's so stupid.

As much as I despise SMS in general, and 2FA over SMS in particular, I think the risk of SIM jacking in the US is pretty low overall for this use-case, which is probably part of why banks don't do more.

Add in (as others have said) the cost of proper 2FA and being able to off-load the risk (which is what banks do), and a VP of Risk Management doesn't have much motivation to drive such a change.

My own anecdotal experience with Sim-jacking and 2FA: I recently ported a number to a new service, properly, with multiple steps to verify I was authorizing the port. It broke every SMS 2FA - I had to login to every account and re-enter the same phone number as my 2FA number. Which required verifying my login with email or another number (that was already in the account).

because its also the most convenient and people are stupid and incapable of handling authenticator apps. plus auth apps are a maintenance burden between phone switching. overall 2fa was a poorly thought out concept to begin with from a end user perspective.

honestly the whole concept of modern 2FA is retarded when you can essentially get the same thing from ssh keys with passwords. (👋 @ passkeys which as basically that renamed)